1. Field of the Invention
The invention relates to an electrical storage system capable of charging an electrical storage device using a direct-current (DC) power supply and an alternating-current (AC) power supply.
2. Description of Related Art
In Japanese Patent Application Publication No. 2012-228060 (JP 2012-228060 A), a system for charging a battery for traveling using a DC power supply is disclosed. In the system, a main contactor (so-called relay) is provided on a main power line connecting the battery for traveling with an inverter. By allowing the main contactor to be turned on, electric power can be supplied to the inverter from the battery for traveling, to enable a vehicle to travel.
In the system disclosed in JP 2012-228060 A, a charging line is connected to the main power line between the main contactor and the inverter, and a charging contactor (so-called relay) is provided on the charging line. A vehicle-side connector connected to the charging line is connectable with a charger-side connector which is connected to a charger including a DC power supply. If the charger-side connector is connected with the vehicle-side connector and the charging contactor is turned on, electric power from the DC power supply can be supplied to the battery for travelling to charge the battery for travelling.
In the system disclosed in JP 2012-228060 A, to supply the electric power from the DC power supply to the battery for travelling, the main contactor has to be turned on as well as the charging contactor. Furthermore, the main contactor is also in the on state during the travelling of the vehicle.
The charging contactor includes a movable contact and a fixed contact. Therefore, the movable contact may adhere to the fixed contact. If the charging contactor keeps being turned on due to the adhesion of the charging contactor, voltage of the battery for travelling will be applied to the vehicle-side connector via the charging line, when the main contactor is turned on for the travelling of the vehicle.
To avoid this situation, it suffices not to turn on the main contactor when the charging contactor is subjected to adhesion. However, if the main contactor cannot be turned on, the battery for travelling cannot be connected to the inverter, and thus the vehicle cannot travel.